Average on contiguos segments of a vector

Question

I'm sure this is a trivial question for a signals person. I need to find the function in Matlab that outputs averaging of contiguous segments of windowsize= l of a vector, e.g.

origSignal: [1 2 3 4 5 6 7 8 9];
windowSize = 3;
output = [2 5 8]; % i.e. [(1+2+3)/3 (4+5+6)/3 (7+8+9)/3]

EDIT: Neither one of the options presented in How can I (efficiently) compute a moving average of a vector? seems to work because I need that the window of size 3 slides, and doesnt include any of the previous elements... Maybe I'm missing it. Take a look at my example...

Thanks!

I edited the question. It seems related somehow, but it doesn't do what I need. — Oliver Amundsen, Feb 15 '17 at 14:44
not good: x = 1:9; y = conv(x, ones(1,3), 'valid')/3; y = 2 3 4 5 6 7 8 — Oliver Amundsen, Feb 15 '17 at 14:49
I edited the title because you are not lookign for a moving average. A moving average is an average at each point of the data, considering a N-window — Ander Biguri, Feb 15 '17 at 14:50
Will originalSignal size be a multiple of widow size, always? — Ander Biguri, Feb 15 '17 at 14:50
Then [`reshape`](https://www.mathworks.com/help/matlab/ref/reshape.html) your signal and use [`mean`](https://www.mathworks.com/help/matlab/ref/mean.html), e.g. `mean(reshape(origSignal, windowSize, []))` — sco1, Feb 15 '17 at 14:51
Ander, thanks.. No, not necessarily. The vector is a time signal, 4 minutes sampling, so the original signal can to be trimmed at the end... — Oliver Amundsen, Feb 15 '17 at 14:53
@OliverAmundsen Then you would need to explain what to do in that case.... Because your example doesnt hold. What happens when `[1 2 3 4 5 6 7 8 ]` — Ander Biguri, Feb 15 '17 at 14:54

Ander Biguri · Accepted Answer · 2017-02-15T15:02:20.603

3

If the size of the original data is always a multiple of widowsize:

mean(reshape(origSignal,windowSize,[]));

Else, in one line:

mean(reshape(origSignal(1:end-mod(length(origSignal),windowSize)),windowSize,[]))

This is the same as before, but the signal is only taken to the end minus the extra values less than windowsize.

edited Feb 15 '17 at 15:02

answered Feb 15 '17 at 14:53

Ander Biguri

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Average on contiguos segments of a vector

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